Charles t



(No Model.)

0. T. PRATT.

DRILL GHUOK.

No. 462,879. Patented Nov. 10, 1891.

64am, fnvmtmr UNITED STATES PATENT OFFICE.

CHARLES T. PRAT", OF CLAYVILLE, NEW YORK, ASSIGNCR TO THE PRATT CHUCK COMPANY, OF SAllIE PLACE.

DRILL-CHUCK.

SPECIFICATION forming part of Letters Patent No. 462,879, dated November 10, 1891.

Application filed March 2.1891. Serial No. 383.492. (N model.)

T0 (0 whom it may OOH Said jaws are removed to enable the strength- Be it known that l, CHARLES T. PRATT, a ening-screws to be clearly shown. Fig. 4 is a citizen of the United States, and aresident of longitudinal elevation of the chuck with the Clayville, in the county of Oneida and State jaws removed. Fig. 5 is a view of the under 55 5 of New York, have invented certain new and side of one jaw, showing the slot through useful Improvements in Drill Chucks, of which a strengthening device passes, and also which the following is a specification. the female threads which engage with the op- My invention relates to improvements in crating-screw. drill-chucks, and more especially to improve- A is a chuck, which is preferably formed of 60 1o ments in that class of chucks which have a steel and in a cylindrical shape and with a chamber or chambers in which the grippingrear part B of somewhat smaller diameter jaws work; and the object of my improvethan the part A. Said part B is bored out for ment is to provide means for strengthening an arbor, (not shown in the drawings,) by the chuck and preventing the spreading of which the chuck is fixed in a lathe. Enter- 65 the walls of said chamber. In general the ing from the front face of the chuck A is a jaws of said chucks are operated by a screw deep chamber C, with parallel side walls 0 c. which engages each jaw on only one side. In this chamber C work jaws D D, and said Now I have found by practical experience jaws are operated by the engagement of their that when the said jaws are forcibly closed female threads cl (1 with the screw E. Said 7c upon the stock of a drill by means of said screw E passes through the chuck A by an screw there is a tendency to tilt the jaws, opening II, which loosely fits said screw E. which then act as Wedges or levers to force Said screw E is formed in the usual manner, apart the walls of the said chamber. As is with two sections e c, united bya spindlef, of well known, the pressure of the jaws on the smaller diameter than the sections cc, and said 75 drill-stock is very great. Consequently a opening H has a central collarn, correspondpowerful force is exerted in the aforesaid ing to the aforesaid spindle f, so that, although manner to spread apart the walls of the said the screw E can turn freely in said opening chamber, which force in time spreads said H, it cannot move lengthwise therein. The walls so as to' seriously damage the chuck. aforesaid sections ,6 e of the screw E have 80 To overcome this difficulty I have devised the one righthanded and the other leftmeans for strengthening the chucks against handed threads of equal pitch, the said the aforesaid spreading action of the jaws, threads engaging the corresponding female which means consist of devices that pass threads d din the jawsDD. Thus byturning through the body of the chuck and across the the screw E in one direction or the other the 8 5 said chamber, so as to tie the walls thereof jaws D D may be made to approach to or retogether and prevent their spreading apart. cede from each other, and said jaws D D each The said devices also serve to limit the play have a rib d, which engages with a recess a of said jaws and prevent said jaws from bein one of the walls 0 of the chamber C for ing accidentally drawn out of the chuck. the purpose of guiding said jaws. Now said 0 Referring to the drawings which accoinscrew E engages with each of the jaws D D pany the specification to aid in the descripon only one side, and there is a tendency to tion, Figure 1 is an end view of the chuck. tilt the jaws D D when they are closed upon The jaws are shown in place and gripping the a drill-stock, as in Fig. 1, and to thereby force ""stock of a drill, and the strengthening dethe walls 0 c apart. To remedy this I pass 95 vices are indicated by dotted lines. Fig. 2 is screws J J, usually two in number, through a longitudinal elevation of the chuck, showholes 7; 7t and Z Z in the chuck A and ing the openings for the strengthening deacross the chamber 0. The ends of eachof vices. Fig. 3 is a cross-section of the chuck on said screws J J are threaded to engage with the lineX Xof Fig. 4., showing the chamber in corresponding threads in the holes it Z, and 100 the chuck and the strengthening devices, as the holes 7; Zare somewhat enlarged near their also the main screw which operates the jaws. outer ends to receive the heads of the screws J J and form shoulders or or, against which said heads of the screws J J come. Now said screws J J being inserted in their several openings k k and Z Z and tightened, it is evident they will serve as ties across the cham' her 0 and will hold the walls a 0 against spreading apart. Of course in place of screws any equivalent device could be used. The said aws D D have slots 0 entering from the outer face of said jaws and of a size to easily fit over said screws J J. The saidjaws D D are first inserted into the chamber 0 and drawn together by the screw E, then the screws J J are passed through the aforesaid holes It 70 and Z Z, and through the aforesaid slots 0 in the jaws D D. The said screws J J are then tightened and the chuck is ready for use. It will be evident from Fig. 5 that the length of the slots 0' limits the amount of movement of the jaws D D, and that the screws J J will prevent the said jaws D D from being accidentally drawn out of the chuck A.

Should the chuck A or jaws D D wear by reason of long usage, so that said jaws do not fit properly in the chamber (J, then by tight ening the said screws J J the walls 0 .c of the chamber 0 may be drawn nearer together, so. that the jaws D D will again fit properly in the chamber C.

It is evident that my invention is not restricted to chucks with only two jaws of the kind shown in the drawings, but is equally applicable to all chucks which have chambers in which any number of jaws work.

strengthening devices in chucks, which devices pass from wall to wall of the chambers in which the jaws work, so as to hold said Walls against spreading.

Now, having described my invention, I claim 1. In a chuck having a chamber for the jaws which grip a drill, a device which passes across the said chamber and engages with both walls of said chamber in order to prevent the spreadingof the said walls, as described.

2. In a chuck having a chamber for the jaws which grip a' drill, devices which pass across said chamber and engage both walls of said chamber in order to prevent the spreading of the said walls, as described.

3. The combination of a drill-chuck having a chamber for the jaws which grip a drill,-

screws crossing said chamber and engaging with opposite walls of said chamber, and jaws working in said chamber and slotted for the passage of said screws, as described.

Signed at Olayville, in the county of Oneida and State of New York, this 14th day of February, A. D. 1891.

CHARLES '.l. PRATT.

\Vitnesses:

G. HUMPHREY, JOHN DEMPSEY.

For my invention, broadly considered, is the use of 

